Weft insertion system for weaving looms

ABSTRACT

A gripper shuttle weaving machine in which a weaving shuttle travels through the shed of warp threads and introduces a weft thread, wherein the shuttle consists of a highly conductive nonmagnetic material (for example aluminum) and is propelled along guide lamellae arranged in the shed by an asynchronous linear motor arranged outside the shed in the direction in which the weft thread is introduced.

United States Patent Jusko et a1. Sept. 2, 1975 54] wEFr INSERTION SYSTEM FOR WEAVING 3,335,300 8/1967 Brimer 310/13 LOOMS 3,376,441 4/1968 Martin et a1. 310 13 Inventors: Josef Jusko; Ernst Grieshaber, both of Schaffhausen, Switzerland Assignee: Georg Fischer Aktiengesellschaft,

Schaffhausen, Switzerland Filed: Apr. 24, 1974 Appl. No.: 463,450

US. Cl 139/134; 139/126 Int. Cl. D03D 49/26; DO3D 49/44 Field of Search 139/11, 125, 126, 188,

References Cited UNITED STATES PATENTS Delgado 139/134 Primary Examirter-Henry S. .laudon Attorney, Agent, or Firm-Flynn & Frishauf [57] ABSTRACT A gripper shuttle weaving machine in which a weaving shuttle travels through the shed of warp threads and introduces a weft thread, wherein the shuttle consists of a highly conductive non-magnetic material (for example aluminum) and is propelled along guide lame]- lae arranged in the shed by an asynchronous linear motor arranged outside the shed in the direction in which the weft thread is introduced.

15 Claims, 13 Drawing Figures PATENTEDSEP 21975 3. 902 5-35 SHEETBUFS COMPRESSED AIR PATENTEDSEP 21915 3 902 535 SHEET Q [If 5 Fig. 6

WEFT INSERTION SYSTEM FOR WEAVING LOOMS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a gripper" shuttle weaving machine in which a shuttle travels through a shed and introduces a weft thread and wherein the shuttle is pro pelled by an asynchronous linear motor.

2. Description of Prior Art Weaving machines, provided with gripper shuttles or bobbin shuttles for introducing the weft thread into the shed, in which the shuttles are propelled by travelling magnetic fields are known. In German Pat. Nos. 813,830; 851,928 and 1,006,357 and Offenlegungsschrift No. 1,535,595 there is described such a weaving machine in which a travelling electromagnetic field is generated by devices arranged along the entire shuttle race by reversible direct-current electromagnets or by a suitably wired alternating-current electromagnetic assembly of suitable frequency. The shuttle, which is in the form of an armature plate or a permanent magnet or which may carry an electromagnet, is driven nonpositively by this travelling magnetic field. In order to reduce the friction forces between the shuttle and the warp threads produced by the relatively high transverse traction of the shuttle, the shuttle is generally provided with rollers or small wheels which travel over the warp threads supported by a flat bearing surface. In spite of this, it is not possible, because of the considerable friction of the weaving shuttle on the shuttle race, to overcome the low drive efficiency and substantially eliminate wear of the bearing surface and the danger of destroying the warp threads. Another disadvantage is that a stator fixed to the sley is used to generate the travelling electromagnetic field over the entire length of the shuttle race and the components of this stator, consisting largely of iron, produce an additional moment of inertia in the movement of the sley. Since iron allows only a limited magnetic flux, relatively large amounts of iron have to be used in the shuttle to provide the necessary thrust forces on the shuttle, which in turn increases the mass to be accelerated which results in a correspondingly high dissipation of energy during braking.

In an alternative form of weaving machine, the shuttle is in the form of a magnetic armature which is guided by ferromagnetic guide plates engaging in the shed, so that the shuttle slides through the shed without coming into contact with the warp threads. The guide plates are also used for supporting the shuttle and for magnetically field-shunting the travelling magnetic field (see German Patentschrifts Nos. 1,066,958 and 1,072,569). Although the danger of warp-thread destruction is largely eliminated, difficulties are nevertheless encountered in designing the guide plates which have to be made in the form of thin lamellae. They have to be both stiff and resistant to wear to prevent them from being deflected and driven by the reaction forces of the shuttle.

The weaving machines described above, in which the travelling electromagnetic field is generated by an alternating current or by a direct current and a collector, generally involve difiiculties with starting up and slowing down the shuttle, because this takes place at low frequencies and voltages but uses high currents. In addition, the shuttle may be asynchronously entrained by the travelling magnetic field.

In US. Pat. No. 2,135,373 there is described a bobbin shuttle weaving machine in which the principle of linear induction, i.e., an asynchronous linear motor, is used for electromagnetically driving the shuttle back and forth through the shed. The weaving shuttle carries the secondary winding corresponding to a known squirrel-cage rotor winding and the necessary magnetic return of highly permeable material, for example, iron. The disadvantage of this embodiment is the effect of the mass of the magnetic return material, in addition to its inherent mass, upon the inertia of the shuttle.

However, it is possible by specially designing the linear motor to transfer the magnetic return material to the fixed stator of the linear motor (UK. Pat. No. 763,362). In this case, the bobbin-carrying part of the shuttle is provided with an additional drive member in the form of a thin non-magnetic metal plate which engages in the air gap of the stator to drive the shuttle. In

one proposed embodiment, the driving and decelerating linear motor system is arranged either over the entire weaving width or only over a part thereof, depending upon the force required. The effect of the additional drive plate is to increase the space occupied by the shuttle, with the result that considerable distances have to be overcome by the sley and the reed because of the relatively wide shed opening. In addition, acceleration and deceleration of the relatively high mass of the bobbin shuttle necessitates relatively high rotor winding currents. The resultant heating of the rotor reduces the efficiency of the drive arrangement, in addition to which the warp thread is in danger of being destroyed.

BRIEF SUMMARY OF THE INVENTION It is an object of the present invention to provide a gripper shuttle weaving machine which obviates the aforementioned disadvantages of conventional weaving machines by removing the relatively heavy stator from the sley and by reducing the inertia of the shuttle.

According to the present invention there is provided a gripper shuttle weaving machine, comprising:

a weaving shuttle consisting essentially of an electrically conductive non-magnetic material; and an asynchronous linear motor, for accelerating the weaving shuttle,

a guide beam within the motor forming a magnetic return path and a trajectory guide for the shuttle; and preferably lamellae-like shuttle guides located in the shed throughout the trajectory of the shuttle.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic view of a linear motor acting as an accelerator. and brake for a shuttle which is in the form of apart of a ring and which is guided in the linear motor by means of a guide beam and in the shed by means of lamellae;

FIG. 2 shows various embodiments of the shuttle in cross-section, namely:

a. in the form of a part of a ring;

b. in the form of a part of a polygon;

c. in the form of a part of a rectangle;

d. in the form of a part of an ellipse;

e. in S form;

f. in the form of a dumbell;

g. in meander form;

FIG. 3 is a diagrammatic vertical section through the shed, with guide lamellae arranged on the sley, for a weaving shuttle in the form of a part of a ring showing the position of the sley during beating-up;

FIG. 4 is a vertical'section through a shuttle guide beam in the linear motor showing an air-cushion for the weaving shuttle;

FIG. 5 is a diagrammatic view of one embodiment of the weaving shuttle with a thread gripper;

FIG. 6 is a diagrammatic elevation of the guide lamellae arranged on the sley for the weaving shuttle (shown in section) according to FIG. 3; and

FIG. 7 is a diagrammatic view, partly cut away, of the windings of the stator of an accelerator and brake.

DETAILED DESCRIPTION OF INVENTION FIG. 1 shows an accelerator 1 and brake 4 for a shuttle 9, both in the form of asynchronous linear motors. The reference 7 denotes the guiding means for a shuttle in the shed which, in the interests of clarity, has not been shown in FIG. 1 in common with the other known components of conventional weaving machines, such as the reed, heddles etc. The reference 9 denotes a shuttle to be introduced into the accelerator l, for example a gripper shuttle, to which the weft thread is attached in a delivery unit (not shown) or which is provided with a length of weft filament adapted to the cloth width. It is then mounted on the delivery beam 1 1 (how this is done is not shown) and introduced mechanically in synchronism with the other units of the weaving machine into a stator 2 of the accelerator 1 where it is accelerated by a travelling magnetic field in the stator 2, leaving the accelerator 1 at the velocity of the magnetic field. A guide beam 3, on which the shuttle 9 is guided, consists of a material of high magnetic permeability, for example lamellae of soft iron, whose contact or bearing surface may be provided with a wear-resistant coating. The guide beam 3 performs two functions: firstly it guides the shuttle inside the stator 2 and, secondly, acts as a magnetic return for the stator 2. After leaving the accelerator 1, the shuttle (denoted by the reference 10 in this position) slides through the shed on guide lamellae 8 of the shuttle guide 7 in the shed. The accelerator 1, like the brake arranged at the opposite end of the shed, is arranged laterally outside the warp or shed. After leaving the shed, the shuttle is guided on a guide beam 6 into a stator 5 of the brake 4 where it is suitable decelerated to a residual velocity, for example electromagnetically by parallel-current or counter-current braking or by oversynchronous braking. The operations known from conventional weaving machines, such as thread deceleration, thread cutting, beatingup, shed change, selvage formation, etc. are carried out in synchronism with shuttle deceleration with corresponding phase displacement. The shuttle 10 leaves the stator 5 of the brake 4 at its residual velocity and returns through a conveyor shown schematically by chain dotted lines C to the delivery unit and to the input end of the accelerator 1.

An asynchronous motor which can be energised by a continuous alternating current at a constant frequency is used to propel the shuttle 9 in the accelerator 1. Control of the firing rate of the shuttles has to be taken over by the mechanical shuttle insertion unit.

In order to minimise idling losses in the stators 2 and 5, i.e., in the shuttle-free linear motor, the air gap 12 (FIG. 7) between the stators 2 and 5 and the guide beams 3 and 6 should be as small as possible. This is achieved by making the shuttles 9 and 10 with thin walls.

In order to further reduce power and energy consumption, the linear motor can also be energised by impulse-like altematingcurrent, in which case the impulse sequence has a pulse repetition rate corresponding to the shuttle insertion rate or frequency.

Energy can also be saved by varying the velocity of the travelling magnetic field during accelaration of the shuttle 9 or 10, for example by locally varying the magnetic pole interval along the acceleration path (without any change in the energising frequency for the linear motor) or by varying the energising frequency for the linear motor during acceleration of the shuttle.

The shuttle 9 is best made with thin walls or is provided at least partly with thin-walled drive surfaces to derive maximum efficiency from the electromagnetic drive. The other properties required for the shuttle 9 or 10 can be obtained by suitable shuttle geometry and by guiding the shuttle in the shed. To this end, the shuttle can assume various forms, as illustrated in FIG. 2. The shuttles 9 and 10 shown in FIG. 1 have the crosssection shown in FIG. 2a, i.e., is in the form of a part of a ring. However, it can assume other cross-sectional forms such as those shown in FIG. 2b to 23. The guide beams 3 and 6, the guide lamellae 8 and the geometrical form of the stators 2 and 5 also have to be adapted to the particular cross-sectional form selected. In addition, the supports 17 for the guide beams 3 and 6 illustrated in FIG. 1 have to be adapted to the particular form selected for the shuttle cross-section.

FIG. 3 is a cross-section through a widely opened shed 13 formed by the warp threads 26, a reed l4 and the guide lamellae 8. The latter two are fixed to the sley 15. After the shuttle 10 has passed through the shed guided by the guide lamellae 8, the sley 15 isturned to the left in the direction of the arrow 16 out of the rest position illustrated into the position shown in broken lines about a pivot arranged below the shed. As a result of this movement, the guide lamellae 8 are swung out of the shed 13, so that only the reed 14 is left in the shed 13 and beats up the weft thread 26' introduced by the shuttle 10 onto the cloth 25.

FIG. 4 is a cross-section through the guide beams 3 and 6 arranged in the stators 2 and 5 and the shuttle 9. Compressed air is admitted to the guide beams 3 and 6, forming a cushion of air between the surface of the guide beams 3 and 6 and the inner surface of the shuttle 9. The compressed air is supplied through a duct 17a in the support 17 for the guide beams. The air is discharged through radial bores 19, which open into an air duct 18 extending axially along the shuttle guide beams 3 and 6, into the air gap 20 between the shuttle 9 and the guide beams 3 and 6.

FIG. 5 diagrammatically illustrates the local arrangement of a thread gripper 21 to resiliently grip the weft thread 26', on the shuttle 9 which has a cross-section substantially of the kind illustrated in FIG. 2a. The

shuttle 9 is provided with conical tapers or rounded edges-22 at each end. In accordance with the openings in the stators 2 and 5 and in the guide beams 3 and 6 and the guide lamellae 8 in the shed match the shape of the geometric form of the thread gripper 21, although in the interests of clarity, these openings have not been so shown in the FIGS. The lateral shuttle sections 23 are primarily used for electromagnetic shuttle acceleration,anddeceleration and for thislpurpose they tixe dly arranged in the shed, in which case the dents of consist of an electrically highlyconductive material, for

example aluminum. FIG. 6.shows the guide achieved with the shuttle cross-sections shown in" FIG. 1

lamellae 8 arrangedfon the, sley 15 at intervals which-depend on the length of the the reed slide past the guide lamellae in order to beat the weft thread. The guide lamellae can also be dey signed to beatu p the weft threa'dQ due to friction- 2 and which canbe seen particularly clearly-from FIGS.-

3 and 4 for the shuttle cross-section illustrated in FIG. 2a, affords the advantage that no problems are involved in distributing the warp threads during the entry and departure of the guide lamellae 8 into and from the shed, because the warp threads cannot become entangled with the guide lamellae.

It is important, in the embodiment described with reference to FIG. 1, to use at least one asynchronous linear motor which is arranged outside the warp or shed in the direction of entry. In this case, the shuttle is guided as required inside the linear motor and either over a part of or over the entire length of the shuttle trajectory through the shed. In cases where an asynchronous linear motor is used for accelerating the shuttle, the shuttle is used as a linear squirrel-cage rotor, in which case the magnetic travelling field is preferably generated by 3-phase alternating current. By arranging the acceleration system in this way, the shuttles can be made with thin walls and at least partly of aluminum, thereby enabling a low shuttle mass to be maintained.

By applying this concept for the gripper shuttle weaving machine in accordance with the invention, the useful load determined by the thread gripper or storage unit and the useful volume of the shuttle are kept relatively low. In this way, it is possible to apply this useful load to the shuttle in such a way that it does not interfere to any appreciable extent with the drive mechanism in the air gap of the linear motor. In addition, the individual gripper shuttles can be controlled in the frequency with which they are used in such a way that intermediate cooling is possible.

If the interrupted hollow form, for example a crosssection according to FIG. 2a to 2d, is used in particular for the shuttle, the stators 2 and 5 can be wound cylindrically in the same way as tubular linear motors. This has the advantage of structural simplicity and of reducing electrical line losses. In addition, the interrupted hollow form of the shuttles 9 and 10 provides for easy access to the shuttle guide beam.

FIG. 7 shows this method of winding on part of the accelerator stator 2. In order to show the winding, some of the stator 2, which consists largely of iron, has been cut away. The cylindrical coils 28 are accommodated in grooves 27 in the stator 2 and also extend through the support 17. The support 17, which consists of a non-magnetic material, engages through the coil assembly 28 and supports the guide beam 3.

In the case of the guide lamellae 8, it is possible, in orfer to protect the guide lamellae 8 against wear and to reduce friction, they are also applied to the corresponding surface of the shuttle.

Instead of using the guide lamellae fixed to the sley, it is also possible to use guide lamellae whose movement is controlled by means of a separate drive shaft. In the case of relatively coarse cloth, they can also be The brake arrangements known from conventional shuttle ,weaving machines can. be combined with a lin- -ear motor. designed to function as an accelerator.

- If, however, brakingis carried out by a unit similar to 1 the accelerator 1, ,it is possible to. apply the .braking methods commonly used in linear motors.

. The use of,linearmotors as accelerator and brake provides for low-noise operation of a weaving machine. Since the shuttles can be made with a very low mass, the firing rate can also be increased without any increase in the consumption of power.

It is to be noted that modifications other than those indicated above may be made to the embodiments described as illustrative of the invention without departing from the scope thereof.

We claim:

1. Weft insertion system for weaving looms comprismg:

a gripper shuttle (9, 10) of electrically conductive non-magnetic material;

an asynchronous linear motor (1), for accelerating the shuttle (9, 10);

a guide beam (3) for the shuttle arranged within the asynchronous linear motor (1), which guide beam is also used for magnetic :return; and

a shuttle guide (7) arranged over the trajectory of the shuttle (9, 10).

2. A system as claimed in claim 1, wherein an asynchronous linear motor (4) is provided for decelerating the weaving shuttle l0).

3. A system as claimed in claim 1, wherein the shuttle guide (7 comprises guide lamellae (8).

4. A system as claimed in claim 3, wherein the guide surfaces of the guide lamellae (8) and the shuttles (9 and 10) are provided with a wear resistant coating.

5. (On printing, to follow claim 6) A system as claimed in claim 3, wherein the guide surfaces of the guide lamellae (8) and the shuttles (9 and 10) are provided with a low friction coating.

6. A system as claimed in claim 1, wherein the weaving shuttle is in the form of an elongated, thinwalled element having a surface which partially surrounds the shuttle guide (7).

7. A system as claimed in claim 6, wherein the crosssection of the weaving shuttle is of a partly open, hollow form.

8. A system as claimed in claim 6, wherein the crosssection of the weaving shuttle is meander shaped.

9. A system as claimed in claim 1, wherein a stator (2) of the asynchronous linear motor (1) is provided with ring-shaped windings (28) arranged in annular grooves (27) in the stator in planes perpendicular to the direction in which the weft thread is to be introduced.

' 10. A system as claimed in claim 1, wherein guide beam (3) comprises an extension (11) arranged on the entry side of the asynchronous linear motor (1).

l l. A system as claimed in claim 1, wherein the guide beam (3) is provided with a pneumatically activated surface for the weaving shuttle (9).

12. A weft insertion systems for weaving looms, comprising:

shuttle, the portion of the, guide beam (3) within the further asynchronous linear motor (4) providing a magnetic return path therefor.

13. A system as claimed in claim 12, wherein a shuttle guide (7) comprising guide lamellae (8') is arranged over the trajectory of the weaving shuttle.

14. A system asclaimed in claim 12, wherein the weaving shuttle is in the form of an elongated, thinwalled element having a surface which partially sur rounds the shuttle guide (7 15. A system as claimed in claim 12, wherein the weaving shuttle consists essentially of aluminum.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 1 3 902 535 DATED September 2, 1975 INVENTOR( 3 Josef J'USKQ, et al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the initial page of the patent, insert the following priority data;

-[30] Foreign Application Priority Data April 27, 1974 Switzerland .6094/73-;

Signed and Scaled this thirtieth Day of December 1975 g [SEAL] Attest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commission" a] hit! and Trademark: 

1. Weft insertion system for weaving looms comprising: a gripper shuttle (9, 10) of electrically conductive nonmagnetic material; an asynchronous linear motor (1), for accelerating the shuttle (9, 10); a guide beam (3) for the shuttle arranged within the asynchronous linear motor (1), which guide beam is also used for magnetic return; and a shuttle guide (7) arranged over the trajectory of the shuttle (9, 10).
 2. A system as claimed in claim 1, wherein an asynchronous linear motor (4) is provided for decelerating the weaving shuttle (10).
 3. A system as claimed in claim 1, wherein the shuttle guide (7) comprises guide lamellae (8).
 4. A system as claimed in claim 3, wherein the guide surfaces of the guide lamellae (8) and the shuttles (9 and 10) are provided with a wear resistant coating.
 5. (On printing, to follow claim 6) A system as claimed in claim 3, wherein thE guide surfaces of the guide lamellae (8) and the shuttles (9 and 10) are provided with a low friction coating.
 6. A system as claimed in claim 1, wherein the weaving shuttle is in the form of an elongated, thinwalled element having a surface which partially surrounds the shuttle guide (7).
 7. A system as claimed in claim 6, wherein the cross-section of the weaving shuttle is of a partly open, hollow form.
 8. A system as claimed in claim 6, wherein the cross-section of the weaving shuttle is meander shaped.
 9. A system as claimed in claim 1, wherein a stator (2) of the asynchronous linear motor (1) is provided with ring-shaped windings (28) arranged in annular grooves (27) in the stator in planes perpendicular to the direction in which the weft thread is to be introduced.
 10. A system as claimed in claim 1, wherein guide beam (3) comprises an extension (11) arranged on the entry side of the asynchronous linear motor (1).
 11. A system as claimed in claim 1, wherein the guide beam (3) is provided with a pneumatically activated surface for the weaving shuttle (9).
 12. A weft insertion systems for weaving looms, comprising: a shuttle (9, 10) of an electrically conductive magnetic material; an asynchronous linear motor (1), located outside of and adjacent to one side of the shed, for accelerating the shuttle; a guide beam (3) for the shuttle arranged within the asynchronous linear motor (1), which guide beam is also used for magnetic return; a shuttle guide (7) arranged over the trajectory of the shuttle (9, 10); and a further asynchronous linear motor (4) surrounding said guide beam and located outside of and adjacent the other side of the shed, for decelerating the shuttle, the portion of the guide beam (3) within the further asynchronous linear motor (4) providing a magnetic return path therefor.
 13. A system as claimed in claim 12, wherein a shuttle guide (7) comprising guide lamellae (8) is arranged over the trajectory of the weaving shuttle.
 14. A system as claimed in claim 12, wherein the weaving shuttle is in the form of an elongated, thinwalled element having a surface which partially surrounds the shuttle guide (7).
 15. A system as claimed in claim 12, wherein the weaving shuttle consists essentially of aluminum. 